Electromagnetic sound apparatus



March 23,1926. 1,577,741 4 A. DU BOlS-REYMOND ET AL i ELECTROMAGNETIC SOUND APPARATUS Fi-led'Jan. 5. 1921 s Sheets-Sheet a manna To all whom it may concern:

Patent ed Mal- 2 3,1 19 26 1 lum'r uo T TES- PATENT-{OFFICE ALABD b nomamdtm, or non, mum m; m mom mm, m,

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i 1 Application -filed January SIGNAL GESELLSCEBI'T I. B H., orxmn,

' monomers-mo somrn APPARATUS.

19a; 'Serial 1%. 435397.

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- Be it knownthat we, ALARD DU Bors-Rnv- Mom and LEONID ADEIMANN, citizens of the GermanRepublic, and residing at Plon, near Kiel, and at Kiel, county of Schleswig- Holstein, and State of Prussia, Germany, have invented certain new and useful Improvements in Electromagnetic Sound Apparatus (for which applications were filed in Germany, July 12, 1915; Feb. '17, 1916;

March 15,1916; Austria, August 12, 1916; August 25,1916; Oct. 4, 1916; Hungary, August-16, 1916; August 31, 19 16; and November l, 1916; and German patents issued Feb. 10, 1918, and March 2, 1918), of

-"which thefollowing is a specification .This invention relatesto electromagnetic sound signalling apparatus and more par;

- ticularly. to submarine sound signalling ap paratus'esuipped with magnets whose active iron is laminated or built up of iron sheets insulated from each other for the purpose of preventing current losses, andheld together by bolts. In all of the known types of such magnets air-gaps remain between the individual sheets or laminae of the finished mag-' net which enable these sheets to vibrate against each other andto thus'give rise to a damping that increases the deleterious damping eifect of the apparatus;

. A knownmethod of holding laminated 7 iron cores together consists in passing pins 1 which are insulated from the iron through receiving sound waves, and the higher the 6 rate of vibration or frequency-is the lessthe sheets'and riveting them atboth' ends, and in providingthick end-plates which are ,fixed by screws tothe. parts towhich the. en: 7 tire laminated iron core is to be attached; J,butthis"method of assembling is not satisfactory in cases where the electromagnet itself is to act as a vibrating part of a-sound; signalling apparatus," i. e;, as .a part ot a vibratory structure'- capable ofproducing or satisfactory this method will be; Th e fact "has'been' revealed that during each vibrationv of the entire laminatediiron core the individual laminae execute separate; motions wlth 1 respect to each otherand insodoing they f consume. so much 'energy' by"fricti on,i"or.- roduce so' large a deleteriousdamping ef-:'

' ect, that it becomes impossible to obtain a; s'ufiicientlysharp tuning of the vibratory structure; Thereasonforthis is that such 1 D -'a pack of metal sheets, when compelled -to execute 'scound vibrations which are .more' rapid than a very low frequency, will only behave like an integral .bodyifthe sheetsare firmly fixed to each other, it being also necessary under certain circumstances to place themf so that their main surfaces extend inthe direction -of the vibrations.

The objector the invention is prevent the individual parts or laminae of such composite vibrating members from moving rel atively towards and away from each other,

or at least to reduce such 'motionto a minimum- This is accomplished by employing special binding agents or means which, with due consideration to the aforementioned points, are so selected and arran ed that. they prevent indivldual motions o the various parts or laminae of which composite bodies, intended to vibrate as a whole, are made up. These methods, means or agents may be of difieren't kinds and may consist:

equivalent binding "agents which bind the laminae so as toform an integral body devoid of any internal damping efiect;

t 3. Incombining the means described in'"1 with that described in 2.

The invention is illustrated in ings'in whichconstructional forms. of apparatus are shown. embodying the aforemen 'tioned methods. drawingsi Fig. 1 is a sectional elevation-and inated. cores being fixed to solid metal-plates by clamping members which; extend in the rFlgs. 1 and 1 aretw ports-r the drawuniting the i Fig. 2a side elevatiomof electromagnets having laminated ironcores whose laminae are soldered togetherat their edges,'the lam:

modifiedlforms in p which the-laminated'core sup I Figs; 3- and 4 except that the molten coatin'gs after they have been worked into the .15 fixed to each other by gumor varnish so as proper shape, are fixed to a back-plate or magnet yoke.

Fig. 6 is an end view of Fig. 5.

Fig. 7 shows a cross section of a part of an apparatus in which a vibrating plate is. connected to an armature of an electromagnet which is composed of iron stampings to form a solid mass.

In Figs. 1 and 2 A and B are metal slabs or plates interconnected byzelastic members such as elastic rods or tubes R. Fixed to the two plates A and B are the laminated iron cores C and D of a subdivided .electro magnet which are intended to vibrate as a whole together with their plates when the active parts of the apparatus are excited by sound producing forces or waves in such a manner as to cause the two divided masses C and D to alternately approach and recede from each other." The sound producing or exciting forces may be generated by means of an electric coil placed in'the slots E and F and periodically-energized by a suitable solder, may be screws 2 LA and B maybe dispensed with; @Another a'dvantageous arrangement, :shown .in g

alternating electric current from an alternatingv current generator (coil .and generator not shown here). The individual sheets of which the core of the electromagnet is built up are provided with integral fastening lugs G and H, and the surfaces a, and 9 formed by theedges of the sheets are made smooth and polished.- Before thecores G and D are fixed to the plates A and B, holders L, M of U-shaped cross section are fitted on to the lugs Gand H of the assembled or stacked laminae and thensoldered to these lugs, preferably with solder of a high melting point. The lugs, after they have thus been combined with treated as solid beams or bars, so' that holes can be drilled through them 'n the main direction in which the individual laminae extend,-after which they be fastened to the .plates A and B by and'k. In this method of joining .the cores .andplates the fixing screwslie may outside the path of-the magnetlclflux, The\. is mine-ted electromagnetcores obtained in thisfmanner vibrate together with their plates or other partstowhichithey, are attached without giving rise to an inordinate damping. Instead of attaching the fixing lugs ,to' plates A, B they may bescrewed or soldered to the interconnecting member's directly as shown infFig. 1, so'that the plates spending-part of the frame 6 electromagnet in'which it is tobe used.

selves instead of separate screws as a means for fixing the packs of laminated iron to the plates A or B, or to a vibrating plate by which sound energy is radiated.

A drawback in the method of joining the various sheets of the bunches C and D by soldering is that it involves very troublesome preparatory operations and can only be carried out by very experienced and conscientious workmen. Another feature of the invention therefore provides a simpler means of joining the sheets, according to which the surfaces to be joined and the fixing lugs are prepared similarly, but in a 'more convenient manner than if they are to be soldered together. This'means consists in coating the sheets or laminae with :i layer of molten iron by welding them to-- gether or by welding additional metal onto them.. Thislayer may be arranged to form either a substitute for the fixing bars (L, M

Figs. 1 and 2), or simply an intermediate layer between the lugs and the fixing bars, which will enable the process of soldering the pack to a back-plate to be carried on "more easily than if the edges of the laminae themselves are directly soldered thereto. These methods of .uniting the laminae and of fixing the complete packs of sheets to their holders are shown in Figs. 3 to 6.

In all these figures C denotes iron horseshoe stampin of thekind ordinarily employed for tie magnetically act1ve laminated cores of electromagnets. In accordance with Fig. 3 the stampings are formed at both ends with fixin lu s H and G which are outside the path and held together by rivets 0;

full lines, are welded onto the fixin lugs by meansof an oxyacetylene or e ectr1c inner surfaces of the iron coatings or casings thus formed are welded to'the edges of the lugs H and G1 of all of the laminae orsheetsC, the pack of sheets is united into a oi? the ma etic flux" oatings of iron P, as indicated in Fig. 3 by irregular -welding apparatus or the like. Since the single body all of whose individual sheets vibrate-in unison in the direction in which each sheet chiefly extends vertical ,in v :the

drawing). After the app ied casings P have cooled down they :are worked-into the and the complete iron core may, ithenbe .treatedas-a single "piece and screwed fast by means of the fastening in s to'a correthe. device or Fi 5 and 6 show a modified construe iron or. yoke of the magnet.

er by pins 0. Thenzthe-wholeback shape indicated by broken lines in Fig. 3

ofthe Pack is covered-with ey coating P is worked into the shape indicated by the solid lines of Fig. 5, and'fixed in the iron block Q. Finally the fissure between P and Q may be filled up by soldering, 'By bridging over the narrow surfaces or edges of the sheets C by means of a coat.-

ing of'metal welded onto them, a uniform clean metallic siu'face is obtained that can be easily soldered. Thus a perfectly reliable connection between each individual stamping C of the pack and the block or backplate Q is obtained, so that the entire piece can then be readily connected to the other parts of theapparatus by screws, or by soldering or welding the joints between the back-pl'ate and the said other part, etc.

In the constructional forms hereinbeiore described it is desirable to so arrange the sheets of the laminated core that their principal suriaces extend in the direction of the vibrations which they are caused to execute.

By the method explained with reference to 25 Big. 7, but applicable 'to all other modifications, this is. rendered unnecessary.

In this figure R is a diaphram or Vibrat ing plate, Q. is, a frame for the pack of plates which is held together by a rivet O. C are the individual'sheets or stampi'ngs, and the spaces between them are filled with gum S. T is a fragment of a casing in the cylindrical wall of which diaphragm R- is fixed.

The varnishes or gums used for filling the interstices between adjacent stampings preferably consist of liquid natural or synthetic gums or solutions such as phenolic condensation products for example; By these all interstices or cavities between. the individual sheets, which might be due to unevenness of the surfaces of the latter, are

7 sheets or core into a vessel completely filled so as to. prevent vibrations of the arts relatively to each other and to unite t e whole into a single body which will operate in a sound signalling or vibagent into. the interstices. When this has been done the described operations are repeated, Finally the gummed body is dried.

If a suitable phenolic condensation product' is used as a binding agent it is introduced into the interstices in a liquid condition at a temperature of about 50 Celsius and dried at a temperature above 150.

It will be obvious that even if the sheets or laminae are united in the manner illustrated in Figs. 1 to 6 they may also be gummed together by inserting a binding agent into the'interstices between them.

2. An electromagnetic system comprising a vibrating member and laminated iron electromagnet cores having portions located outside of the normal magnetic flux path and adapted to cooperate with theyibrating member, the laminae of the iron cores extending in the direction of the Vibrations of the vibrating member and being welded together at said outside portions by means of metal applied to the said edges-in molten state, and a solid iron body to which at least one of the said coresis welded.

An electromagnetic system comprising a vibrating member and laminated iron electromagnet coreshaving portions located outside of the normal'magnctic flux path and adapted to cooperate with the vibrating member, the laminae of the ironcores being welded together at said outside portions.

4. An electromagnetic system comprising a vibrating member and laminated iron electromagnet cores having portions located outside of .the normal magnetic flux path and adapted to cooperate with the vibrating member, the lamina: of the iron cores extending in the direction of the vibrations of the vibrating member and being welded together at said outside portions.

5. An electromagnetic system comprising avibrating member and laminated ironelectromagnet cores adapted to cooperate with the vibratin member, said laminae having lateral fixing lugs outside of the normal magnetic flux path and being welded together at the outer edges of said lugs.

Intestimony whereof we have affixed our signatures.

A. DU BOIS-REYMOND. LEONID ADELMANN.. 

